You’ve heard the claims: men are inclined to cheat on women because natural selection favors multiple offspring from multiple mates, especially if you don’t have to pay child support. Even rape has been suggested to be the result of natural selection in favor of “secondary mating strategies” when the primary ones fail. Welcome to evolutionary psychology, a discipline curiously situated at the interface between evolutionary science and pop psychology, where both wild and reasonable claims seem to clash against the wall of an incredible scarcity of pertinent data.

The issue is not whether it makes sense to apply evolutionary principles to the study of human behavior. Of course it does, human beings are no exception to evolution. But the devil is in the details, and the details deal with the complexities and nuances of how exactly evolutionary biologists test adaptive hypotheses, as well as with the nature of historical science itself.

Reader Comments (8)

I agree with much of what is said in the episode, but would like to point out a couple of things: evolutionary psychologists don't in particular try to study why humans are unique and it's quite the contrary. Ev psychs study humans because they want to see how certain universal evolutionary mechanisms are at work. In the heart of evolutionary psychology is the notion that sexual selection and natural selection work on humans as well as on any other animal. True. we don't know many things (such as why our brain is so big) but we can postulate good hypotheses that can be tested. Massimo seems to dismiss mate choice as something that isn't really what evolutionary psychologists do, which is quite odd since there are so many studies that yiled novel findings coming from evolutionary psychologists. And yes, we might not know for sure a lot of things, but nonetheless we can have pretty good idea if some trait might have evolved mechanism even if it's not yet completely understood.

Another thing that is also sort of misconception about the field is that the focus is on universality, In fact. evolutionary pscyhologist stress adaptive responses to different environments by comparing life in the western word with non traditional populations for example.

Massimo says that testing human universals results in a sample size of exactly one, but this is inaccurate. Each culture is one of the members of the sample, and the fact that all cultures have each human universal means that the hypothesis has been tested many times (once per culture).

I'm not sure why the alleged focus on the Pleistocene is such a big deal. Most Evolutionary Psychology hypotheses would work in other primitive environments since selection pressures would be similar - the key environmental factor in the Environment of Evolutionary Adaptation would be humans living in a tribe in a hostile world; whether we evolved in grasslands or forests, our predilection for foods high in fat/sugar would be equally explained; while the way current hunter-gatherers live is not going to be identical to how our ancestors did, it's the best we have to go on.

One irony I've noticed is that people who criticse evolutionary psychology often say that human evolution proceeds faster than evolutionary psychologists think. However, these would seem to be the same people who stress the unity of mankind and deny that human races exist (if human evolution does indeed move so quickly, you'd think that we would see distinct human populations).

I don't know why Massimo went on about how evolutionary psychology does not explain the size of the human brain - this is not within its remit, but that of evolutionary biology!

In Evolutionary Psychology, we can't perform phylogenetic analysis - because the human mind is so complicated, we are not sure which genes map to which behaviors (and anyway, it's not a neat one-one match). In fact, even with animals I believe this is hard. However, we *do* compare human and animal behaviors. IIRC, there's been a comparison of cuckolding. Animal prostitution and animal rape have also been observed.

It is ironic that Massimo seizes upon disagreement between the authors of A Natural History of Rape as evidence that their thesis is flawed. Does it matter whether Rape is an adaptation or a sprocket? Science has disagreements. Indeed, Creationists seize on disagreements in the field of Evolutionary Biology as a way of discrediting Evolution (this is the irony I mentioned) - for example the debate about Evolution by Creeps or Jerks.

Lastly I'd comment that popular science in general is sloppy - not just on Evolutionary Psychology. I will single out Satoshi Kanazawa as particularly unsubtle and simplistic, though.

Rationally Speaking is a pretty good podcast, but Massimo and Julia discuss topics they don't always know much about. The podcast is at its best when experts are invited to speak.

This particular podcast was frustrating to listen to, because a few of the things Massimo said about evolutionary psychology are not true. Rather than spreading misconceptions, why don't you guys invite an expert in evolutionary psychology onto the podcast? You could invite David Buss or Robert Kurzban, for example.

There are some good comments here already, which I mostly agree with. I'll just add that evolutionary psychology is an empirical science that generates testable hypotheses. Not being able to figure out absolutely everything about the evolutionary history of human behavior is no reason to just give up, as Massimo implies we should.

These are all good comments. The only detail I'd add, which I think got lost too often in this podcast, and tends to in general, is that behaviour does not evolve. That's not the evolutionary psychology position. Rather, it is computational rule sets that tend to channel behaviour which evolve. The distinction is important, because, once you make it, you can recognize that in any specific, objective set of environmental conditions different rule sets can be activated. As such, these rule sets can modify or even countermand each other.

For instance, certainly infidelity can provide fitness advantages -- to males or females. However, a stable, secure, trusting monogamous parenting relationship can, too. Which strategy is going to win out is going to depend on a host of complex and interacting objective conditions, computationally evaluated (unconsciously, of course) in relation to the specific situation in which the individual is living.

I find this is the single most common area of confusion on the part of those first trying to educate themselves on evolutionary psychology. And, it is the favoured red herring of the most superficial critics. It is behind the widespread silliness that evolutionary psychology endorses or legitimizes or soft pedals rape, homicide, war, etc.

Incidentally, for anyone who is interested, I'm just beginning to launch my own little project on the topic. You can check it out here: http://theevolvedpsyche.com/ if interested.

Men might have an innate desire to mate with multiple women more than women want to mate with multiple men, but another possibility exists. While both women and men have genitalia, both have gonads (ovaries and testes), and reproductive vessels (fallopian tubes and vas deferens / epididymis), ONLY the female has a uterus. Thus, without any innate evolutionary psychological behavior, a female will realize that her own pregnancy may result as an important consequence of sexual intercourse. The cognitive ability displayed by any healthy woman can by itself completely account for female hesitation from engaging in random sexual intercourse. With contraception, however, the rate of casual sexual encounters has risen enormously, thus demonstrating that perhaps women actually have a libido quite similar to men.